The present invention relates to a method of manufacture of an RFID, in which a semiconductor chip having individual identifying information stored in a memory is bonded to an antenna member.
A conventional method of manufacture of an RFID is disclosed in Japanese Unexamined Application JP2003-203946(A). According to the method of manufacture disclosed in this document, first, an un-annealed aluminum foil is placed on one side of a PET (polyethylene terephthalate) film, with the intervention of a urethane resin adhesive, which is bonded to form a laminated structure through a thermal lamination process under the condition of 150° C. and 5 kg/cm2, and, thereby, a metal foil laminated material is manufactured. Further, the metal foil laminated material is overlaid with a thermoplastic resin adhesive. And, ultrasonic vibrations are applied to a semiconductor bare chip with gold bumps to further heat it to 150° C., and the semiconductor bare chip is bonded to the metal foil of the metal foil laminated material that is covered with the thermoplastic resin adhesive.
The method of manufacture disclosed in the above-referenced document disregards the influence of the temperature on the metal foil laminated material during the mounting of the semiconductor chip. In this regard, the glass transition temperature of the PET is 60° C.˜80° C. in general, and, when the temperature of the PET film exceeds this glass transition temperature, the PET film becomes rubbery.
The above-referenced document discloses the ultrasonic bonding of a metal foil adhered to the PET film and the semiconductor chip under the ambient temperature of 150° C.; accordingly, the PET film softens like a rubber material during the bonding. When the PET film softens, the metal foil is deformed. If the metal foil undergoes a serious deformation, the metal foil will be peeled off or short-circuited, which possibly gives an undesirable deviation to the frequency characteristic of the antenna. This problem develops when using a PEN (polyethylene naphthalate) film or a sheet of paper as the base material, although the temperature and the degree of deformation are different.
Therefore, an object of the present invention is to provide an RFID in which deformation of an antenna having a low heat resistance property is reduced.